1. Field of the Invention
The present invention relates to a disk brake for a vehicle used in a motor vehicle or a motor bicycle, and more particularly to a structure of a pad retainer that supports lug pieces of a back plate of a friction pad by pad guide grooves of caliper support arms.
2. Description of the Related Art
In a disk brake in which lug pieces respectively protruding at both side parts of a back plate of a friction pad are supported by pad guide grooves formed and opposed to each other in a pair of caliper support arms so as to move the friction pad in the axial direction of a disk, a pad retailer formed with a metal thin plate is ordinarily interposed between the pad guide grooves and the lug pieces. In such a pad retainer, a pad retainer is known that includes resilient parts abutting on the lug pieces to urge the lug pieces toward sides opposite to a disk rotor and urge the lug pieces toward outer side surfaces of the pad guide grooves in the radial direction of the disk, so that the pull-back and the backlash of the friction pad are suppressed by them (for instance, see Japanese Patent No. 3934063).
Further, as an attaching structure of a pad retainer to caliper support arms, an attaching structure is known that pad retainer attaching parts are provided in outer sides of pad guide grooves in the radial direction of a disk, end parts of outer side pieces of the pad retainer in the radial direction of the disk arranged in the outer side surfaces of the pad guide grooves in the radial direction of the disk are bent along end surfaces of the pad retainer attaching parts and extended to the outer side surfaces of the pad retainer attaching parts in the radial direction of the disk to form attaching pieces and the pad retainer attaching parts are sandwiched between the attaching pieces and the outer side pieces in the radial direction of the disk to attach the pad retainer to the caliper support arms (for instance, see JP-A-2000-161401).
In the structures disclosed in Japanese Patent No. 3934063 or the JP-A-2000-161401, the sliding resistance of the lug pieces of the friction pad can be reduced or the backlash can be suppressed by the pad retainer. In a vibration arising during an ordinary driving of a vehicle, the lug pieces of the friction pad can be held at prescribed positions in a stable way by an urging force of resilient parts of the pad retainer. However, when the vibration larger than an ordinary vibration is applied to a vehicle body, for instance, when the vehicle gets over a stepped part during the driving, occasionally, the friction pad temporarily moves inside in the radial direction of the disk against the urging force of the pad retainer, then, is urged outside in the radial direction of the disk by the urging force of the pad retainer and the surfaces of the lug pieces collide with the outer side surfaces of the pad guide grooves in the radial direction of the disk through the pad retainer to generate cronk noise (collision noise).